Heat exchanger

ABSTRACT

A heat exchanger for a refrigeration circuit comprising a plurality of parallel tubes bent in an accordion shape, and a plurality of parallel heat exchange fins running transverse to the tubes. The heat exchanger is advantageously mounted in a vertically extending casing, and heat exchange medium is directed upwardly over the tubes and fins to absorb heat transferred therefrom.

iiniteel States lPatent [1 1 iilepltinson 1 HEAT EXCHANGER [75] inventor: Harold H. liliopltinson, Manlius,

[73] Assignee: (Iarrier Corporation, Syracuse, NY.

[22] Filed: May 16, 1973 [21] Appl. No: 366,703

[52] US. Q5. 165/145, 62/507 [5 1] lint. Ci. F251) 39/04 [58] Fieid at Search 165/122, 145;

[56] References Cited UNITED STATES PATENTS 2,401 918 6/1946 Elder 165/145 [45] Aug 6, 1974 Primary ExaminerMcyer Perlin Attorney, Agent, or Firm-J. Raymond Curtin; D. Peter Hochberg [57] ABSTRACT A heat exchanger for a refrigeration circuit comprising a plurality of parallel tubes bent in an accordion shape, and a plurality of parallel heat exchange fins running transverse to the tubes. The heat exchanger is advantageously mounted in a vertically extending casing, and heat exchange medium is directed upwardly over the tubes and fins to absorb heat transferred therefrom.

3 Claims, 2 Drawing Figures HEAT EXCHANGER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to refrigeration heat exchangers, and in particular to fin-tube condensers.

2. Description of the Prior Art Compression refrigeration systems, such as those used in air conditioning apparatus for conditioning the interior spaces of buildings, comprise an evaporator, a compressor, a condenser and an expansion device, connected to form a refrigeration circuit. Refrigerant circulates therethrough, absorbing external heat while passing through the evaporator, and disseminating heat while passing through the condenser. When such systems are used for conditioning small spaces such as individual rooms, small residences, and mobile homes, the components of the system are housed in a common casing. On the other hand, systems used for conditioning larger spaces are commonly split to isolate the condenser and other components from the evaporator, to improve the efficiency of the system and to reduce the indoor space requirements for the equipment. Accordingly it is a known practice to mount the condenser and the compressor in an exterior (outdoor) location wherein space considerations are not a serious factor, and to house the evaporator indoors where it can absorb and remove ambient heat. The evaporators and condensers in these refrigeration systems generally consist of a flat slab of parallel refrigeration tubes running in one direction and heat exchange fins running perpendicular to the tubes. This is known as a slab coil. Slab coils used as condensers are generally mounted either perpendicular to or parallel to the ground, and heat exchange medium such as air is directed through the coil by a fan. Heat exchangers of the foregoing type have generally been adequate for their intended purposes.

With both types of systems there are situations where it is desirable to reduce the length of the evaporator and of the condenser, particularly where the air conditioning system is to be used in an environment where space is at a premium. Existing state of the art appara-' tus has rendered such length reduction difficult, since decreasing the size of the heat exchanger would appear to reduce the heat exchange capacity of the equipment below the level at which it has been designed to function.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a compact heat exchanger for use in a refrigeration circult.

It is a further object of the invention to provide a compact fin-tube heat exchanger which is efficient in transferring heat between refrigerant therein and an external heat exchange medium.

Other objects will be apparent from the description to follow and from the appended claims.

The foregoing objects are achieved according to the preferred embodiment of the invention by the provision of a slab fin-tube condenser which is bent or folded into an accordion shape whereby the length to depth ratio is relatively low when compared to the conventional slab coil arrangement. The condenser finds its main use in refrigeration systems wherein refrigerant in the condenser gives off its heat to ambient air passing over the refrigerant tubes of the condenser. The folded condenser is advantageously mounted vertically in a casing having an air inlet at its lower portion and an air outlet at its upper portion, whereby air is directed vertically upwardly over the condenser tubes and fins.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a split air conditioning system incorporating the present invention.

FIG. 2 is a pictorial view of a condenser assembly according to the preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In its preferred embodiment, the present invention comprises a slab condenser folded into an accordion configuration whose planar surfaces are transverse to the flow of air or other heat exchange medium passing over the condenser for removing heat therefrom. The condenser is mounted in a casing having an air inlet at its base for admitting air for upward flow over the condenser, and an outlet at its upper portion for the warmed heat exchange medium. Although the condenser is shown as used in a split system, it finds like applicability in integral systems as well.

Referring now to the drawings, FIG. 1 shows a typical refrigeration circuit in which the present invention can be incorporated. The circuit includes a compressor 1 for compressing and discharging hot refrigerant'gases to a condenser 3, wherein the refrigerant gives off heat, condenses, and is discharged to a receiver 5; an expansion device 7 through which liquid refrigerant proceeds from the condenser; and an evaporator 9 wherein the expanded refrigerant absorbs ambient heat and evaporates. In split systems which are frequently used to condition the air within residences and other buildings, the evaporator and expansion device are disposed within the building. The compressor, condenser, and receiver are mounted in a separate housing which is normally located outside of the building so that outdoor air can be used for removing heat discharged by the condenser. Also, this arrangement enables the motors associated with the apparatus to be kept out-ofdoors where their noise is less disturbing. FIG. 1 depicts a split system in which the evaporator and expansion device are mounted in a housing 11, and the compressor, condenser and receiver are mounted in a separate, outdoor housing 13.

In both split systems and self-contained or integral air conditioning systems, it is sometimes desirable to render the condenser portion of the system as compact as possible. The foregoing may be dictated by the space requirements of the building, such as where the air conditioning system is to be incorporated in a mobile home or where the system or the condenser portion thereof is to be built into an exterior portion of the building itself. However, the size of the condenser must be commensurate with the required dissipation of heat. Therefore, the condenser must have a sufficient surface area over which air or other heat exchange medium can pass to remove heat therefrom.

With the foregoing considerations in mind, the present inventor arrived upon the condenser configuration illustrated in FIG. 2. The figure shows pictorially the portion of an air conditioning system which was designated by the numeral 13 in FIG. 1. A condenser 3 is shown which has an accordion shape and a Z-shaped profile (when there are only two folds) when viewed in cross section. Condenser'3 includes a plurality of parallel tubes 15 for conveying refrigerant in a heat exchange relationship with ambient air or other heat exchange medium. Tubes 15 extend from their open lower ends (which can be connected to a lower header) to U-shaped tubes or hairpins 17 at their upper ends which connect pairs of the tubes as is conventional in this art. Tubes E can be connected to form one or a plurality of refrigerant flow paths through condenser 3. Refrigerant from compressor 1 enters an inlet to each of the flow paths in condenser 3 from a header (not shown) and is discharged from an outlet of each path to receiver 5 as also is conventional in the art. A plu-' rality of parallel heat exchange fins 19 run transverse to tubes throughout the length of the tubes for enhancing the dissipation of heat from refrigerant within tubes 15.

In the embodiment shown in FIG. 2, condenser 3 is mounted vertically within a housing 21 having an air inlet 23 at the base thereof, so that air can flow upwardly through the condenser over the tubes 15 and fins W. Housing 21 also contains compressor 1 and receiver 5. A fan assembly is provided in the condenser housing in order to obtain a sufficient flow rate of air therethrough. Accordingly, a pair of blowers 25'are mounted above condenser 3. Each blower comprises a blower wheel 27 mounted in a scroll or casing 29. Blower wheels 27 can advantageously be driven by a common motor 31 from which shafts 33 extend. When blower wheels 27 rotate, air is drawn axially within the wheels through inlets 35, and air is discharged from the assemblies and from housing 21 through outlets 37 disposed near the top of the housing.

Thus, when the system is operating, air is drawn into inlet 23 by convection and under the influence of blowers 25. The air stream makes several passes through condenser 3 by virtue of the folds therein. The amount of heat transferred to a given quantity of air diminishes as the air rises through the condenser because the air temperature increases in the course of its travel. This factor must be taken into consideration when designing the size of the condenser.

The condenser in the foregoing embodiment has a low height to depth ratio (length being understood as the dimension transverse to the folds, and depth" referring to the amplitude of the folds) compared to that of the conventional slab coil, whereby it can be installed in otherwise inaccessible, impractical locations. Condenser 3 can be fabricated by simply bending a conventional slab coil, or each of the folds can be manufactured separately and the tube ends joined by appropriately curved tubes at each of the folds. When condenser 3 is mounted in housing 21 as shown, it is readily accessible for cleaning, either by the provision of a door in the casings or by the dismantling thereof.

Although the embodiment of the invention described above is a condenser for a split air conditioning system which incorporates a blower for forcing air over the coil, the invention is not so limited. Folded condensers of the aforementioned type can find great utility in selfcontained units. The blower or other fan can be dispensed with to reduce the expense of the unit where the required capacity of the condenser does not dictate a height which is not commensurate with the space available for the condenser. Moreover, evaporators, particularly fin-tube evaporators, can similarly be configured with the preceding accordion shape to render them compact. in addition, such heat .exchangers can find utility in systems other than compression refrigeration systems, such as in absorption refrigeration systems.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

I claim:

, 1. A heat exchanger for use in a refrigeration circuit, said heat exchanger comprising:

a plurality of parallel tubes for conveying refrigerant in heat exchange relationship with anexternal heat exchange medium to effect the transfer of heat between the refrigerant and the heat exchange medium, said tubes being connected at their end portions to form at least one refrigerant flow path through said heat exchanger and bent into an accordion shape to divide said heat exchanger into a plurality of generally planar sections, contiguous sections being transverse to each other whereby the heat exchanger is rendered compact; and

a plurality of parallel plate fins extending transverse to said tubes for transferring heat between said tubes and the external heat exchange medium.

2. The invention according to claim 1 wherein said heat exchanger is a condenser for an air conditioning system, and said tubes transfer heat from the refrigerant to the external heat exchange medium.

3. A condensing unit for passing refrigerant in heat exchange relationship with a heat exchange medium to effect the transfer of heat from the refrigerant to the heat exchange medium, said condensing unit comprismg:

a condenser including a plurality of vertically extending parallel tubes for transferring the refrigerant, said tubes being connected to form at least one refrigerant flow path and bent into an accordion shape to divide said heat exchanger into a plurality of generally planar sections, contiguous sections being transverse to each other;

a plurality of parallel fins extending transverse to said tubes for transferring heat from said tubes to the heat exchange medium;

a housing for directing the heat exchange medium upwardly over said condenser to absorb heat from refrigerant in said tubes, said housing including a heat exchange medium inlet in the lower part thereof and a heat exchange medium outlet in the 3 upper part thereof; and

a fan in said housing for forcing the heat exchange medium over said condenser. 

1. A heat exchanger for use in a refrigeration circuit, said heat exchanger comprising: a plurality of parallel tubes for conveying refrigerant in heat exchange relationship with an external heat exchange medium to effect the transfer of heat between the refrigerant and the heat exchange medium, said tubes being connected at their end portions to form at least one refrigerant flow path through said heat exchanger and bent into an accordion shape to divide said heat exchanger into a plurality of generally planar sections, contiguous sections being transverse to each other whereby the heat exchanger is rendered compact; and a plurality of parallEl plate fins extending transverse to said tubes for transferring heat between said tubes and the external heat exchange medium.
 2. The invention according to claim 1 wherein said heat exchanger is a condenser for an air conditioning system, and said tubes transfer heat from the refrigerant to the external heat exchange medium.
 3. A condensing unit for passing refrigerant in heat exchange relationship with a heat exchange medium to effect the transfer of heat from the refrigerant to the heat exchange medium, said condensing unit comprising: a condenser including a plurality of vertically extending parallel tubes for transferring the refrigerant, said tubes being connected to form at least one refrigerant flow path and bent into an accordion shape to divide said heat exchanger into a plurality of generally planar sections, contiguous sections being transverse to each other; a plurality of parallel fins extending transverse to said tubes for transferring heat from said tubes to the heat exchange medium; a housing for directing the heat exchange medium upwardly over said condenser to absorb heat from refrigerant in said tubes, said housing including a heat exchange medium inlet in the lower part thereof and a heat exchange medium outlet in the upper part thereof; and a fan in said housing for forcing the heat exchange medium over said condenser. 